The semiconductor device may be a semiconductor package with a structure having a semiconductor chip, such as an IC chip or LSI chip, mounted on a lead frame, and sealed with an insulating resin. For such semiconductor devices, along with advancements in high-integration and miniaturization, their package structures have developed through such types that had an external lead projecting out of a lateral wall of a resin package, as in an SOJ (small outline J-leaded package) and a QFP (quad flat package), to such types that have an external lead buried for exposure at the backside of a resin package, without projecting outside, and are thin and need a small implementation area, as in a QFN (quad flat non-leaded package) and an SON (small outline non-leaded package).
As lead frames, there are known those (e.g. Japanese Patent Application Laying-Open Publication No. 11-40720 (page 4, FIG. 1): patent material-1) having a structure in which, for a frame substrate to be sealed with an insulating resin, its surfaces are treated for a roughing, and a nickel (Ni) layer and a palladium (Pd) layer are laminated in this order on the surfaces by a plating method. As a method for the roughing process, substrate surfaces of lead frame are chemically polished by an etching solution of an organic acid system.
As other known lead frames, there are those (e.g. Japanese Patent Application Laying-Open Publication No. 2004-349497 (Page 7, FIG. 3): patent material-2) in which frame substrate surfaces are covered with a plated Ni skin roughed at the obverse side. Formation of such a roughed Ni skin is allowed by adjusting a condition of the plating method.
Such being the case, the combination of formation of a plated Ni skin over the surface of a lead frame and provision of Pd or Au plated thereon has a wide use for manufacturing processes to be simplified, and environment-oriented processes to be free of Pb.
Further, as circuit members to be brought into close contact with an insulating resin, among others besides lead frames, there are e.g. conductor plates or bus bars of connectors employable in an electrical connection box for distribution of a vehicular power supply to vehicle-mounted auxiliary equipment.